Desulfurization of various effluent gases contemporarily poses a serious problem even though the problem, at least in theory, is subject to rather direct and seemingly simple solutions. However, to carry these solutions into practical effect has been at best difficult. For example, chemical treatments which have been proposed are unusually wasteful of treating reagents and normally pose serious disposal problems because of the large amounts of spent waste which are involved. The more sophisticated chemical treatment methods also require significant amounts of relatively expensive reagents. Other methods have been proposed which involve recovery of the SO.sub.2 component as a valuable product. One such method is disclosed in the Roberts et al U.S. Pat. No. 3,511,027, and involves a system employing water to cool effluent gases and absorb SO.sub.2 therefrom. The SO.sub.2 is later stripped and recovered as a valuable product. It may be used, for example, directly for the production of sulfuric acid or it may be liquified, as mentioned in the patent.
The Roberts et al patent discusses various prior chemical treatment processes and correctly notes that a recovery system involving water to absorb the SO.sub.2 with subsequent desorption to liberate the SO.sub.2 represents an approach which is superior to the various chemical treatment systems described. However, the Roberts et al system although basically sound, does require a rather severe penalty in the form of the large energy expenditure required to practice the disclosed technique. The Roberts et al method also creates operating difficulties and inefficiencies because of the intermixing of various flows and a lack of temperature balances.